After 1946, the WISMUT Company developed the third-largest uranium-mining province in the world in the German Democratic Republic.
Methods: A case-control study among former WISMUT miners was conducted to investigate the lung cancer risk in relation to attained age, time since exposure, exposure duration, and exposure rate. It consisted of 505 patients with lung cancer and 1,073 controls matched to cases according to the year of birth. The cumulative exposure to radon and radon decay products was calculated as the sum of yearly exposures and expressed in Working Level Months (WLM). Cases had a mean cumulative exposure of 552 WLM compared to 420 WLM in controls.
Results: There was a statistically significant increase in lung cancer risk for cumulative exposures above 800 WLM. Under the assumption of a linear risk model, there was a significant increase in the relative risk of 0.10 per 100 WLM after adjusting for smoking and asbestos exposure. For current smokers the increase in relative risk was lower (0.05 per 100 WLM), whereas it was higher (0.20 per 100 WLM) among nonsmokers and longtime ex-smokers. After correcting in a sensitivity analysis for the fact that the controls of this study had a higher average exposure than the population of WISMUT workers they were recruited from, the adjusted ERR increased to 0.24 per 100 WLM. Lung cancer risk declined with time since exposure, except for exposures received 45 or more years ago. No inverse dose rate effect was observed.